Internal combustion engine



oct. 29, 1935. J, E CAS'TLE 2,018,944

INTERNAL lGOMBUSTION ENGINE Oct. 29, 1935. .1. E. CASTLE INTERNAL COMBUSTION ENGINE 2 sheets-sheet 2 Filed May l5, 1953 ATTO alEY Patented Oct. 29, 1935 UNITED STATES PATENT -OFI-Ica 2 Claims.

This invention relates to engines and particularly to inernal combustion engines.

Under present practice, ignition of the compressed charge occurs either immediately on completion of the compression stroke or with a quite slight advancement or retardation relative to such compleion. Consequently the crank shaft is on dead center, or substantially so, at the moment of ignition and does not afford adequate leverage to the expanding gases. 'I'he leverage increases as the shaft advances a quarter turn from dead center position but, in the meantime, the gases rapidly lose energy through expansion.

Sufficient retardation of the spark to establish ample crank shaft leverage upon ignition is prohibited, in present constructions, by the resultant loss of compression.

An object of the invention is to'increase the engine emciency by effecting ignition when the crank shaft is sufficiently beyond dead center to oifer ample leverage to the explosive force, while maintaining compression at its maximum.

Another object is to provide for increasing the volume of the charge over present practice.

Still another object is to increase the efficiency, as aforesaid, by forming the combustion chamber between the usual piston, which drives the crank shaft, and an auxiliary piston driven thereby, the latter being timed in its travel to recede from the former on the suction stroke, thus increasing the charge-receiving space, and to follow up the usual piston as it reccdes from the limiting position of its'compression stroke, to a position in which ignition concurs with adequate crank shaft leverage.

A further object is to adapt said auxiliary piston to be cam operated by a shaft, which also carries cams for actuating the intake and exhaust valves of the engine.

A still further object is to employ said auxiliary piston as a mounting for the intake and exhaust valves. l

These and various other objects, the invention attains by the construction hereinafter described and illustrated in the accompanying drawings, wherein:

Fig. l vis a view of the improved engine in axial vertical section, showing the pistons in firing position.

Fig. 2 is a view -of the same in end elevation.

Fig. 3 is an enlarged vertical sectional view, showing the position of the parts at completion of the working stroke.

Fig. 4 is an axial vertical section taken on the line 4-4 of Fig. 3.

(Cl. 12S-78) Fig. 5 is a cross sectional view of the engine cylinder, taken on line 5--5 of Fig. 4.

Fig. 6 is a vertical section taken on line 6--6 of Fig. 5, and showing the position of the parts on completion of the exhaust stroke.

Fig. 7 is a vertical section taken on line I-I of Fig. 5 and showing the position of the parts on completion of the intake stroke.

In these views, the reference character I des. ignates a cylinder of an internal combustion en- 10 gine, 2 the crank case thereof, 3 the crank-shaft, formed with a crank I, and 5 a connecting rod adapting said shaft to be driven by the usual piston 6 working in said cylinder.

The cylinder is elongated to accommodate an auxiliary piston I having a comparatively short strokev and timed in its travel to recede from the pistonv 6 during the intake stroke, and to follow up the piston 6 following compression and preceding ignition, to remain fixed during the working stroke and assume a position during the exhaust stroke to barely clear the piston 6 as it completes such stroke.

Thus the piston 1. is driven by a cam 8, xed on a cam shaft 9, which is driven from the crank shaft through a drive chain III or the like, at half the crank shaft speed. The shaft 9 preferably passes through a chamber II formed in the upper portion of the piston 1, and is journaled in suitable bearings I2 oppositely formed on the cyin- 30 der. Openings I2a are oppositely formed in the wall of the chamber I I to accommodate the shaft 9 and to provide for initial insertion or replacement of the cam 8 and the other cams hereinafter described.

'I'he cylinder has a removable head I3 bol'ed at Il to the cylinder block, and seating on the latter preferably in the axial plane of the cam shaft. 'I'he cam 8 has a leading segment of constant radius extending preferably through seven- 40 y ty-ve degrees, and a trailing spiral segment extending through ninety degrees, peripherally merging with the leading segment and progressively increasing in radius reversely to its direction of rotation. 'I'he lower wall of the chamber 45 I I is concaved to a radius slightly exceeding that of the leading portion of said cam, and projecting from said wall, centrally thereof is a` roller I5 for engagement by the cam 8.

'I'he timing is such that the cam 8 actuates the 50 piston 'I toward the piston 8 during the major portion of the compression stroke and during the initial portion of the working stroke, establishing the lowermost position of said piston 'I when the crankshaft has rotated a desired distance beyond dead center, as for example thirty degrees. (See Fig. 1.) The charge is then fired and the upper piston is maintained in said position during the working stroke of the piston 6.

As the piston 6 enters upon its exhaust stroke, (Fig. 3), the trailing spiral segment of the cam 8 engages the roller I5 on the piston 1, effecting a slight further advance of the latter toward the iston 6. Thus, as the latter completes its exhaust stroke, only a very slight 4clearance is. afforded between the two pistons and there is hence assured a substantially complete scavenging of the spent gases.

For retracting the piston 1, there is mounted fast on the shaft 9 a pair of cams I6, positioned one at each side of the cam 8, and similarly elongated radially of said shaft.. Said cams have their longitudinal axes in the meeting plane of the leading and trailing portions of the cam 8 and are effective during the suction stroke to move the piston 1 to the raised position shown in Fig. 7. In performing said function said cams engagev bridging members I1 which extend diametrically across the top of the piston 1, said members being centrally slotted at I8 to freely accommodate the cam 8, when raised.

In the lower face of the piston 1 there are formed a pair of valve chambers I9 and I9a within which exhaust and intake valves 28 and 2I, respectively, are adapted to seat upwardly. Said valves are individually carried by stems 22 and 22a, respectively, vertically slidable in the piston and acted yupon by springs 23 to normally-'seat said valves. Passages 24 and 24a respectively lead from the chambers I9 and Isa, respectively and operi' in opposite side faces of the piston and respectively communicate in predetermined positions of the piston with intake and exhaust passages 25 and 26 respectively which open through the cylinder wall.

For opening the valves 2D and 2I at the proper times, the shaft 9 carries cams 21 and 28 at opposite sides of the lifter cams I6.' 'I'he intake valve cam 21 is radially elongated with its longitudinal axis in the radial plane of the trailing edge of the cam 8 and the exhaust valve cam 28 forms a quadrant conforming in radius to the leading segment of the cam 8, and registering substantially with the trailing segment of said cam, lengthwise of the shaft.

Thus as the piston 5 begins its intake stroke, the cam 21 rides upon the stem 22 to open the intake valve 20 and serves to hold said valve open throughout the intake stroke, the piston 1 in the meantime being lifted by the cams I6.' A shoulder 29 on the cam 21 permits the 'intake valve to snap shut as the intake stroke is com-g pleted, (see Fig. 7).

The exhaust control cam 28 rides upon the exhaust valve stem 22a as the piston 6 begins its exhaust stroke, moving the exhaust valve 2I to open position, and maintaining such position throughout said stroke. As the exhaust stroke is completed, the cam 28 rides clear of said stem 22a, permitting the exhaust valve to snap shut, (see Fig. 6).

It is preferred to form the top portion of the cylinder of slightly enlarged diameter and to correspondingly increase the diameter of the chambered top portion II of the piston 1, whereby said portion may more readily accommodate the described cams.

Rotation of the piston 1 is prevented by a suitable arrangement which, as illustrated, comprises a pair of splines 29a driven vertically in grooves in the enlarged upper portion of the cylinder I and having a. sliding fit in corresponding grooves diametrically opposite each other in the enlarged portion ofthe piston 1.

A spark plug 30 is. so mounted in the side wall of the cylinder I that when the pistons 6 and 1 are in firing position, the space therebetween containing the fully compressed charge will register with a recess 3l in said wall, which receives the points of said plug.

Since the described engine is adapted to receive and compress a larger charge than in present practice and affords a considerable leverage to the explosive force at the moment of ignition while establishing maximum compression at such moment, it is apparent that a large increase of engine eiliciency is accomplished.

The invention is presented as including all such modifications and changes as come-within the scope of the following claims.

- 1. An internal combustion engine comprising a cylinder, a primary piston working in said cylinder, a shaft, a driving connection from said piston to said shaft, an auxiliary piston working in said cylinder andforming with Ithe primary ipiston an expansible pressure chamber, a-cam shaft diametrically journaled in" said cylinder, cams upon said shaft for raising and lowering the auxiliary piston in timed relation to the travel of the primary piston, intake and exhaust valves mounted in the auxiliarypiston, means for delivering fuel to saidA pressure chamber under control of said-intake valve, means for discharging combustion gases from said pressure chamber under control of saidv exhaust valve, and

cams on said cam shaft for actuating said intake 45 and exhaustvalves.

2. An internal combustion'eng'i'ne comprising a cylinder, a vprimary pistonworking in'said cylinder, a main shaft, a driving connection from said piston to said shaft;`an auxiliary piston workingin said cylinder and forming-with the 50 main shaft, and cams on said cam shaft within said cam chamber, effective to raise and lower the auxiliary piston in timed relation tothe primary piston.

JOHN EVERETT CASTLE. 

